Consider the triangle elimination problem. We are given a graph G = (V, E), and want to find the smallest possible set of vertices U V such that deleting these vertices removes all the triangles (i.e. cycles of length 3) from the graph. Prove that the following algorithm is a 3-approximation algorithm for this problem: While there is still a triangle C left in G: Delete all the three vertices of C from G End While Output the set of the deleted vertices